Due to that wireless network is capable of mending the defects of wired network, currently the network topology system based on the wireless network protocol of IEEE 802.11, that is, to develop topology system of wireless network according to the inter-connection framework of access points (AP for short) has become the main trend of the development of the wireless network. However, the network topology based on the wireless network protocol of IEEE 802.11 is still without a standard protocol of IEEE and even the related proposal is not decided yet for the development thereof is out of the IEEE's anticipation at the time said protocol is proposed. Thus, numerous network companies have engaged in developing their own topology system of wireless network.
A wireless network is so much different from a wired network in essence that services provided by wireless network and wired network differ from each other, and there are certain potential problems when the wireless network is integrated with wired network. Compared with the topology of wired network, most of the existing topology systems of wireless network developed by network companies are not satisfying for the users, not only inflexible but also with some problems regarding building network, generating topology and network management etc. which are also confronted and waiting for solutions when developing topology system of wireless network under wireless distribution system (hereinafter WDS for short).
Besides, the performance of a wireless network system highly depends on the topology thereof due to that the medium of a wireless network is a limited resource commonly shared and based on the scheme of carrier sense multiple access with collision avoidance (CSMA/CA for short), thus it's very important to share the wireless bandwidth efficiently. Furthermore, interference and noise can affect the transmission performance of a wireless link as well. According to related studies, one more wireless link added will cause the transmission performance to diminish by half, even the wireless network may not be optimized that it could be in busy all the time but with poor performance due to the generated topology.
To solve the problems stated above, the inventor has proposed and filed three patent applications (R.O.C. application no. 094109930, 094120743 and 094133467) which regard to give access points default address group IDs to form a topology system of wireless network and designate an access point linked with a wired network as a root access point to serve all the back-end pure access points through negotiation while other access points linked with the wired network without providing back-end service as backup access points. Thus, pure access points of the same group may determine at any time whether the root access point still exists, and when it doesn't, any one of the backup access points of the same group linked with the wired network may be designated the root access point for providing back-end service through negotiation so as to solve the problems stated above.
However, please refer to FIG. 1, the inventor has found out that under the prior art of the third embodiment of the R.O.C. application no. 094120743, when access points AP6 and AP7 are linked with the same wired network, and access point AP6 is designated as a root access point while access point AP7 as a backup access point, a loop may be prevented because access point AP7 doesn't provide link service for back-end pure access points as access point AP6 does, but access point AP6 will have to afford the dataflow of five back-end pure access points. So, regarding the topology system of wireless network mentioned above, there are still certain problems as follows:
1. Not every root access point linked with the wired network provides service to the back-end pure access points which diminishes the overall performance of the wireless network.
2. The links of the dynamic topology system of wireless network are not properly arranged, i.e. the dynamic topology system of wireless network is with high complexity which results in the overall loading thereof can't be reduced efficiently.
3. The hop count of a frame during wireless transmission is not reduced, and therefore there is still certain interference during the transmission process which diminishes the overall performance of the wireless network.
4. The loading of the root access point linked with the wired network can't be reduced efficiently (Note: The root access point is the one with the highest possibility of congestion.), and because all dataflow of the dynamic topology system of wireless network is transmitted to the wired network through the same root access point, the loading of the dynamic topology system of wireless network could be very heavy and can't be averaged (balanced).
5. The topology system of wireless network of FIG. 1 operates on a single channel which leaves other channels unused.
6. Only when default address group IDs are given to access points can the topology be formed automatically.
Hence, while a plurality of root access points are linked with a wired network, how to make a back-end access point choose an appropriate root access point to link with according to the transmission status of all kinds of signals to form a less complicated topology system of wireless network, reduce the hop count of an access point when linking with the wired network and joining said network topology so as to gain better transmission efficiency, substantially reduce system loading and probable interference, optimize the links of the wireless network, and solve the problems of wasting the bandwidth and unbalanced loading have become important issues waiting for solutions for all wireless network companies.